1. Field of the Invention
This invention relates to an image processing system and an information processing system for receiving data from a number of host systems via a number of input interfaces and processing the received data.
2. Description of the Related Art
Hitherto, several arts of sharing an input buffer to handle data input through a number of input interfaces have been disclosed. For example, an art of dividing a large memory area into small blocks for management, thereby changing the input buffer capacity of a printer without again turning on power is disclosed in Japanese Patent Unexamined Publication No. Hei 7-144442.
Further, an input method of data through a number of interfaces is described. In this method, however, if data input through one interface occupies all the input buffer, data cannot be input through any other interface, causing an increase in the load of a host system and a busy state leading to an inoperative state.
Generally, the input buffer capacity is increased as means for shortening the duration of a problem such as the inoperative state caused by the busy state. For example, an art of changing the input buffer capacity in response to the input interface selection condition for improving the use efficiency is disclosed in Japanese Patent Unexamined Publication No. Hei 6-305204 and a method of analyzing the contents of input data and changing the input buffer capacity depending on whether the data is code or bit map data is disclosed in Japanese Patent Unexamined Publication No. Hei 6-44014.
However, if a time slice function of a multitask operating system is used to execute simultaneous input of data into an input buffer shared among input interfaces, the input buffer size needs to be changed during the data input. The "simultaneous input" mentioned here is defined as data input through more than one interface within a minute time interval like 0.1 seconds.
To share an input buffer at the simultaneous input time, an art of enabling host systems to specify how an input buffer of a printer having a number of input interfaces is shared is available as disclosed in Japanese Patent Unexamined Publication No. Hei 5-100803. In this art, while one of the host systems connected to the printer is outputting data, if another host system starts outputting data, it becomes necessary for the host systems to conduct input buffer capacity negotiations with each other. This causes the printer function to depend on the host systems, impairing the general versatility of the printer itself.
Also, an art of enlarging the buffer size when that an input buffer is full is sensed is disclosed in Japanese Patent Unexamined Publication No. Hei 7-210365. However, when simultaneous input into the input buffer is executed through input interfaces, if the input buffer size is enlarged for each input interface, the buffer size required for another process is limited, thus causing a problem of lowering the performance.
Further, an art of changing the allocation amount of a reception buffer having a fixed capacity to each of input interfaces is disclosed in Japanese Patent Unexamined Publication No. Hei 6-305204. However, in such an art, if the allocation amount is changed freely, a specific input interface monopolizes the reception buffer, making it impossible to input data from any other input interface.